to setup

  clear-all

​

  ; add paticles

  create-turtles number-of-particles [

    set shape "circle"

    set size 0.5

    setxy (min-pxcor + 5) 0

    set color red

    fd random-float 1

  ]

​

  if types-of-particles = 2 [

    ask n-of int (number-of-particles / 2) turtles [

      set color yellow

    ]

  ]

​

  ; make chambers

​

  ask patches with [pxcor < 2 and pxcor > -2] [set pcolor blue]

  set diffusion-coefficient 0.5

​

​

  reset-ticks

​

end

​

to random-walk

​

  ; take a step forward through fractional distance less than 1

  fd random-float diffusion-coefficient

​

  ;randomize direction (heading) for the next step

  rt random 360

​

end

​

​

to go

​

  ifelse trace-path? [

    ask turtles [pen-down]

  ]

  [

    ask turtles [pen-up]

  ]

​

   ask turtles [

    ; if you are near a blue wall or an edge , turn back, else do the random walk

​

     if patch-ahead (int diffusion-coefficient + 1)= nobody [

      set heading 90

      fd 1

    ]

     if [pcolor] of patch-ahead (int diffusion-coefficient + 1) = blue [

      set heading 270

      fd 1

    ]

     random-walk

     ; additional movement depending on the charge 

     if (color = read-from-string color-with-positive-charge) [

       if (xcor + strength-of-the-field) > min-pxcor [          ; to make sure that the particle does not move beyod the edge of the world

       set xcor  (xcor + strength-of-the-field)

       ] 

     ]

      if (color = read-from-string color-with-negative-charge) [

       if (xcor + strength-of-the-field) > min-pxcor [          ; to make sure that the particle does not move beyod the edge of the world

       set xcor  (xcor - strength-of-the-field)

       ] 

     ]

  ]

​

  tick

​

end